June 3, 2008
AP
OKLAHOMA CITY (AP) — There have been more Oklahoma reports of tornadoes so far in 2008 than typically occur in an entire year, according to preliminary data from the National Weather Service.
Photo: Jerry Taylor speaks on his cellphone Saturday May 24 near Marshall, Okla., after his home was hit by a tornado. (By Billy Hefton, The News & Eagle /AP)"The atmosphere is sort of switched on to tornadoes or switched off," said Harold Brooks, a research meteorologist at the National Severe Storms Lab in Norman. "This year, we're on."
Less than halfway through the year, Oklahoma has had 54 tornado reports. A total of 53 tornadoes hit the state in the average calendar year. There have been six tornado deaths in the state this year, which is more than in any year since 1999.
The USA as a whole also has seen far more tornadoes and tornado deaths than usual, with 1,258 tornadoes and at least 110 deaths reported so far in 2008. That's more deaths than in any year in a decade, and a "huge number" of tornado deaths for modern times, Brooks said.
The national death toll this year already is more than twice the 20-year average, said Greg Carbin, warning coordination meteorologist at the NOAA Storm Prediction Center, also in Norman. In the last three years of full data, the average number of tornadoes has been 1,159.
The meteorologists said the high numbers could be linked to long-term trends in weather and climate, such as climate change or La Nina, which is a weather pattern associated with ocean temperatures.
But overall, active tornado years are just hit or miss, the meteorologists said, in part because their formation is dependent both on regional weather systems and local conditions, which actually spark the twisters.
Climate change could increase the frequency of severe storms, Carbin said, but it may also reduce wind shear, which occurs when winds of different speeds or temperatures pass each other. Wind shear is a key ingredient in tornado formation, he said, so how those two factors balance is unclear.
